Chi-Yu King - Böcker

It has been documented for many centuries that earthquakes and other tectonic processes have hydrological effects.  The magnitude and the spatial and temporal patterns of such signals recorded by scientific instruments in modern times have not always been straightforward to explain, and hence remain the subject of active research, especially those that might be precursors to earthquakes. This volume contains 9 papers that present new observations on earthquake-related hydrological, geochemical, and geophysical changes in Japan, Taiwan, Baja California in Mexico, and mostly China, one paper on laboratory rock-mechanics study, and a brief overview of Chinese research on earthquake prediction during the past 5 decades.  Some of the observed changes occurred several days before earthquakes, and are explained with the consideration of heterogeneity of the earth's crust and earthquake-related slow-slip events, with earthquake forecasting as a possible application.

La Reunion is an oceanic intra-plate volcanic island located at the southern-most part 0 of the Mascarene Basin at 21 0 07' S, 55 32' E (Figure 1). It lies south of the Mascarene Plateau and Mauritius Island but is a distinct topographic feature on the rather flat ocean bottom of the Mascarene Basin, whose age is paleocene in the vicinity of the island (Schlich, 1982), and whose lowest point is more than 4000m deep. La Reunion is ellip- tical in shape (50 X 70 km) with a NW-SE elongation. It is composed of two volcanoes: Piton des Neiges and Piton de la Fournaise. A third volcanic structure has been recent- ly discovered on the east submarine flank of the island (Unat et aI. , submitted). Piton des Neiges, a dormant and deeply eroded volcano, rises to a height of 3069 m and oc- cupies the northwestern two-thirds of the island. Piton de la Fournaise (2630 m), one of the most active basaltic volcanoes in the world, began to grow more than 3. 5 X 1O~ years ago on the southeast flank of Piton des Neiges. The evolution of Piton de la Fournaise (Chevallier and Bachclery, 1981) is marked by the formation of three sub-concentric nested calderas (Figure 2).The boundaries of the two older calderas are more or less buried or eroded.

"The Hiroshi Wakita, Volume I" is a collection of original papers regarding the role of terrestrial fluids in earthquake and volcanic processes. This pure and applied geophysics volume provides the results of some of the most recent studies on terrestrial fluids involved in both processes. It honors Hiroshi Wakita for his scientific contributions. Volume II will be published later in 2006. Both volumes are of value to researchers and graduate students in the field.

Terrestrial fluids, earthquakes and volcanoes: The Hiroshi Wakita Volume II is a special publication to honor Professor Hiroshi Wakita for his scientific contribution to science and commemorate his 10th anniversary as Emeritus Professor at The University of Tokyo. This second special issue of Pure and Applied Geophysics consists of 10 original contributions written by researchers from Japan, Germany, Italy, Costa Rica, Sweden, El Salvador, Turkey, USA, Greece, and Spain. The discussed subjects include research on earthquake-related hydrologic and geochemical observed temporal changes, diffuse degassing in active tectonic and volcanic settings, the observed changes on gas emission and temperature prior volcanic eruptions, magma degassing signature in the groundwater system of active volcanic, and the development of recent technology for continous monitoring of volcanic gases. The Hiroshi Wakita volume II will be useful to students and professional researchers who are interested in the role of terrestrial fluids in earthquakes and volcanic activity.